In a Wireless Communication system in which the wireless networks have a choice of operating on channels with different channel bandwidth, the likelihood of one wireless network operating on a wide bandwidth overlapping another wireless network operating on a narrow bandwidth is high. Here, the spectrum of the narrow band channel forms a portion of the wide band channel.
In situations where the interference between the two networks is high, one possible solution to reduce the interference could be to move one or both networks to non-overlapping channels, provided such channels exist. Both networks will become aware of the interference, possibly due to deteriorating throughput or by other means. It is relatively easier for a device operating on the wide channel to determine the exact characteristics of the narrow band channel by using techniques including but not limited to FFT analysis. On the other hand, due to limitations such as channel-filter etc., placed on the receiver of the devices operating on the narrow band channel, it is much harder for these devices to correctly detect the exact characteristics of the wide band channel. In all wireless communication systems, the number of available wide band channels is limited and in many cases might even be limited to one. In such cases, where there does not exist an alternative wide band channel, it makes more sense for the network operating on the narrow band channel to shift to another non-overlapping channel.
Traditionally, if the controller device of a network (an AP of a WLAN network, or a base station of a cell) wants to switch channels, it needs to perform various forms of scans (energy detection, active/passive beacon detection etc.) in order to determine which of the available channels is best. The controller device can spend substantial amount of time and energy in this process. If the controller device had a prior knowledge of the exact characteristics of the interfering wide band channel, it can save substantial time and energy in the scan process since it can safely skip scanning the channels overlapped by the wide band channel.